R. Scott King, BSME
Automotive/Mechanical Engineering Consultant ::::
The operator of a passenger vehicle lost control and struck a neighbor’s house. The vehicle was modified with hand controls for use by a disabled person. After the incident, the operator reported the vehicle accelerated unexpectedly and uncontrollably, causing the incident that led to his injuries. A post-incident inspection revealed evidence consistent with a pre-existing defect in the newly installed hand controls with the potential to cause the controls to bind. This binding condition could prevent the accelerator linkage from closing, thus leading to unexpected vehicle acceleration.
The vehicle was equipped with a factory-installed event data recorder (EDR) that recorded the last eight seconds of brake pedal application, and the last five seconds of throttle application and vehicle speed, prior to the incident. The recovered data indicated the throttle was applied, and remained applied for the duration of the recorded event, which was consistent with the operator’s post-incident statement. However, data also suggested a steady increase in throttle position, combined with intermittent brake pedal application. Thus, the EDR information was somewhat inconsistent with a purely stuck throttle; rather, it indicated potential operator error.
The hand control installed on the vehicle utilized a single hand lever for both accelerator and brake control. Pushing the lever straight down applied the brakes while rotating the handle in a counter- clockwise arc controlled the throttle. This design permitted an infinite combination of positions wherein both brakes and accelerator could be applied simultaneously. Indeed, this was consistent with the EDR information, as well as the operator’s testimony.
Experts for the plaintiff opined the hand control design was defective for permitting simultaneous application of brake and accelerator through a single control device, and that the installation was defective for failure to maximize hand control effectiveness resulting in a settlement.